Water feeding device of instantaneous heating type and control method thereof

ABSTRACT

A water feeding device of instantaneous heating type electrically connected an external power source includes a water tank, a transparent pipe, a heating module, a contactless sensing module, and a control module. The transparent pipe is connected between the water tank and the heating module. The heating module converts electrical energy of the external power source to thermal energy. The contactless sensing module disposed at an outside of the transparent pipe includes a lighting unit and a light sensing unit. The lighting unit produces a light beam toward the transparent pipe. The light sensing unit disposed opposite to the lighting unit detects intensity of the light beam propagating through the transparent pipe to generate a detection signal accordingly. The control module electrically connected to the heating module and the contactless sensing module controls the heating module whether to continuously produce the thermal energy according to the detection signal.

BACKGROUND

1. Technical Field

The present disclosure is related to a water feeding device, and inparticular to, a water feeding device of instantaneous heating typecapable of detecting whether the water line of the water tank issufficient, and a control method thereof

2. Description of Related Art

Currently, with the development of the human life quality, therequirement for the drinking water in usual life is increasing. Theconventional manner for obtaining hot water by heating unboiled waterthrough the gas oven or electric oven is replaced by the manner forobtaining the hot water by using the water dispenser or the thermos,wherein the water dispenser or the thermos can provide the cold and hotwater simultaneously.

However, to meet the requirement that the water dispenser or the thermosmust feed water to the user on the go, a heater is used to heat theunboiled water injected into the hot water bile to make the waterboiled, and continuously heat the boiled water, such that thetemperature of the hot water in the hot water bile can be maintained ata predetermined temperature degree (such as 80 or 100 centigradedegrees).

Although water dispenser or the thermos provides the convenience for theuser to draw the hot water, the unnecessary power is wasted since thehot water in the hot water bile should be maintained the predeterminedtemperature, and thus the power saving policy dedicated by thegovernment cannot be observed.

In addition, the usage amount of the hot water required by the uservaries with the season or period, for example, the usage amount of thehot water in winter is larger than that in summer. Thus, if the waterline of hot water in the hot water bile is maintained the full waterline, the power consumption is increased to maintain the temperature ofthe hot water in the hot bile the specific at the predeterminedtemperature degree, and thus the practical usage requirement and theefficient usage manner are not met.

SUMMARY

An exemplary embodiment of the present disclosure provides a waterfeeding device of instantaneous heating type and a control methodthereof, wherein an optical contactless sensing manner is used to detectwhether the water tank continuously provides the water flow to theheating module, and when that there not water flow feeding to theheating module is detected, the heating module is turned off, so as toassure the operation safety of the water feeding device of instantaneousheating type.

An exemplary embodiment of the present disclosure provides a waterfeeding device of instantaneous heating type. The water feeding deviceof instantaneous heating type is electrically connected to an externalpower source, and comprises a water tank, a transparent pipe, a heatingmodule, a contactless sensing module, and a control module, wherein oneend of the transparent pipe is connected to the water tank, another oneend of the transparent pipe is connected to the heating module, and thecontactless sensing module is disposed at an outer side of thetransparent pipe. The heating module converts electrical energy of theexternal power source to thermal energy, so as to heat the water flowinjected from the water tank. The contactless sensing module comprises alighting unit and a light sensing unit, wherein the light sensing unitis disposed opposite to the lighting unit. The lighting unit is used togenerate a light beam toward the transparent pipe, and the light sensingunit is used to detect intensity of the light beam propagating throughthe transparent pipe to generate a first detection signal accordingly.The control module is electrically connected the heating module and thecontactless sensing module, receives the first detection signal, andcontrols the heating module whether to continuous produce the thermalenergy according to the first detection signal.

An exemplary embodiment of the present disclosure provides a controlmethod used in a water feeding device of instantaneous heating type, thewater feeding device of instantaneous heating type is electricallyconnected to an external power source, and has a water tank, atransparent pipe, and a heating module, wherein the transparent pipe isdisposed between the water tank and the heating module, the heatingmodule is used to converts electrical energy of the external powersource to a thermal energy. The control method comprises steps of:generating a light beam toward the transparent pipe; detecting intensityof the light beam propagating through the transparent pipe, andgenerating a first detection signal accordingly; and controlling theheating module whether to continuously produce the thermal energyaccording to the first detection signal.

To sum up, the exemplary embodiments of the present disclosure provide awater feeding device of instantaneous heating type and control methodthereof. Since the refraction indices of the water and air differentfrom each other, the water feeding device of instantaneous heating typeuses a contactless sensing module disposed at an outside of thetransparent pipe connected between the water tank and the heating moduleto detect whether the water flow continuously flows into the heatingmodule. When that the water flow does not flow into the heating moduleis detected, the heating module is turned off and stop generating thethermal energy.

In order to further understand the techniques, means and effects of thepresent disclosure, the following detailed descriptions and appendeddrawings are hereby referred, such that, through which, the purposes,features and aspects of the present disclosure can be thoroughly andconcretely appreciated; however, the appended drawings are merelyprovided for reference and illustration, without any intention to beused for limiting the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the present disclosure, and are incorporated in andconstitute a part of this specification. The drawings illustrateexemplary embodiments of the present disclosure and, together with thedescription, serve to explain the principles of the present disclosure.

FIG. 1 is a function block diagram of a water feeding device ofinstantaneous heating type according to one exemplary embodiment of thepresent disclosure.

FIG. 2A is a lateral view showing practical operation of the contactlesssensing module according to one exemplary embodiment of the presentdisclosure.

FIG. 2B is a lateral view showing practical operation of the contactlesssensing module according to another one exemplary embodiment of thepresent disclosure.

FIG. 3 is a function block diagram of a water feeding device ofinstantaneous heating type according to another one exemplary embodimentof the present disclosure.

FIG. 4 is a lateral view showing a water line sensing module and a watertank according to one exemplary embodiment of the present disclosure.

FIG. 5 is a flow chart of a control method used in the water feedingdevice of instantaneous heating type according to one exemplaryembodiment of the present disclosure.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Reference will now be made in detail to the exemplary embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numbers areused in the drawings and the description to refer to the same or similarparts.

[Exemplary Embodiment of Water Feeding Device of Instantaneous HeatingType]

Referring to FIG. 1, FIG. 1 is a function block diagram of a waterfeeding device of instantaneous heating type according to one exemplaryembodiment of the present disclosure. As shown in FIG. 1, the waterfeeding device of instantaneous heating type A comprises a water tank 1,a pump 2, a transparent pipe 3, a heating module 4, a contactlesssensing module 5, and a control module 6, a gas/liquid mixing module 7,and an outlet 8, wherein the transparent pipe 3 is connected between thewater tank 1 and the pump 2, the contactless sensing module 5 iscorrespondingly disposed at an outside of the transparent pipe 3. Inaddition, the pump 2 is connected to the heating module 4, thegas/liquid mixing module 7, and the outlet 8, and the pump 2, theheating module 4, and the contactless sensing module 5 are electricallyconnected to the control module 6. In practical operation, the waterfeeding device of instantaneous heating type A should be electricallyconnected to an external power source (not shown in the drawings), suchthat the water feeding device of instantaneous heating type A canoperate normally. However, that the external power source is a powersource of a direct current (DC) or alternative current (AC) type is notused to limit the present disclosure. Each function module of the waterfeeding device of instantaneous heating type A is depicted with thefollowing detailed descriptions.

The water tank 1 is detachably installed on the upper side of the waterfeeding device of instantaneous heating type A and connected to one endof the transparent pipe 3. The water tank 1 is used to stores the liquidto be heated by the water feeding device of instantaneous heating typeA. The water storage amount of the water tank 1 is not used to limit thepresent disclosure. In addition, the radius and shape of the transparentpipe 3 are not limited, for example the transparent pipe 3 can be arectangular pipe, a spiral pipe, or an irregular curved pipe.

The pump 2 is connected to another one end of the transparent pipe 3,and used to draw the water flow stored in the water tank 1 to theheating module 4. In the exemplary embodiment, the pump 2 is controlledby the control module 6, and determines whether to continuously draw thewater flow from the water tank 1 to the heating module 14 according to afirst control signal generated by the control module 6. Practically, thepump 3 can be a volumetric pump, a kinetic pump, or an electromagneticpump, and the type of the pump 3 is not used to limit the presentdisclosure.

The heating module 4 is connected to the transparent pipe 3 through thepump 2, and used to convert electrical energy of the external powersource to thermal energy, so as to heat the water flow injected from thewater tank 1. Practically, the heating module 4 is usually formed by ablock structure and a plate structure, wherein the block structure isused to make the water flow generate turbulence, and the plate structureis used to heat the water flow flows thereon. However, the presentdisclosure is not limited by the practical structure of the heatingmodule 4 and the material of the above structure.

Please refer to FIG. 2A and FIG. 2B, the disposed position and theoperation of the contactless sensing module 5 are depicted in details,wherein FIG. 2A is a lateral view showing practical operation of thecontactless sensing module according to one exemplary embodiment of thepresent disclosure, and FIG. 2B is a lateral view showing practicaloperation of the contactless sensing module according to another oneexemplary embodiment of the present disclosure. As shown in FIG. 2A andFIG. 2B, the contactless sensing module 5 is disposed at an outside ofthe transparent pipe 3, and used to detect whether the transparent pipe3 transmits the water flow to the heating module 4. To put itconcretely, the contactless sensing module 5 comprises a lighting unit50 and a light sensing unit 52, wherein the lighting unit 50 is disposedat an arbitrary position of the outside of the transparent pipe 3, andthe light sensing unit 52 is disposed opposite to the disposed positionof the lighting unit 50, such that the connection lime of the lightingunit 50 and the light sensing unit 52 passes through the central axis ofthe transparent pipe 3.

The lighting unit 50 is used to generate a light beam L toward thetransparent pipe 3. Practically, the lighting unit 50 can be a lightemitting diode (LED), a laser diode (LD), or an organic light emittingdiode (OLED), and the present disclosure is not limited thereto. Thus,the type of the light beam L generated by the lighting unit 50 does notlimit the present disclosure, for example, the light beam can be ainfrared light, a ultraviolet ray, a visible light with any color, or alaser beam.

The light sensing unit 52 is used to detect intensity of the light beampropagating through the transparent pipe 3 to generate a first detectionsignal accordingly. Practically, the light sensing unit 52 can be aphotodiode, a photoresistor, a charge coupled device (CCD), a colorsensor, or an ambient light sensor (ALS), and the present disclosure isnot limited thereto.

In practical operation, since the refraction indices of the air andwater are different from each other, such that when the light beam Lgenerated by the lighting unit 50 propagates through the transparentpipe 3, a refraction phenomenon may thus happen. As shown in FIG. 2A,the transparent pipe 3 does not transmit the water flow drawn from thewater tank 1, that is, the interior and the exterior of the transparentpipe 3 are surrounded by the air. Thus, when the light beam L propagatesthrough the transparent pipe 3 to be detected by the light sensing unit52, since the medium of the interior and the exterior of the transparentpipe 3 are air, the refraction phenomenon of the light beam L does nothappen. Furthermore, since the light beam L of any type would havegradual scattering property (p.s. the light beams L of different typeshave different scatter levels) during propagation, the energy of thelight beam L is gradually dispersed, such that the light sensing unit 52merely detects little portion energy of the light beam L.

As shown in FIG. 2B, the transparent pipe 3 transmits the water flowdrawn from the water tank 1, that is, the interior of the transparentpipe 3 is full of the water flow, and the exterior of the transparentpipe 3 is surrounded by the air. Thus, when the light beam L propagatesthrough the transparent pipe 3 to be detected by the light sensing unit52, based on Snell's law, the refraction phenomenon of the light beam Lwill happen, since the light beam L propagates to another medium (suchas water flow) with different refraction index from the original medium(such as air). In the exemplary embodiment, since the light beam Lsequentially propagates through the air, the water flow, and the air,refraction phenomenon of the light beam happens twice. To put itconcretely, when the light beam L propagates from the air to thetransparent pipe 3 full of the water flow, since the refraction index ofthe water (about 1.33) is larger than the refraction index of the air(about 1), based on the Snell's law, between the interface of the airand the water, the incident angle of the light beam L in the air islarger than the refraction angle of the light beam L in the water, suchthat the energy of the light beam L propagating in the water is morecondensed the energy of the light beam L propagating in the air, and thelight sensing unit 52 detects much portion energy of the light beam L.In other words, when the light beam L propagates through the transparentpipe 3, and the transparent pipe 3 transmits the water flow, owing tothe refraction phenomenon of the light beam L, the intensity of thelight beam L detected by the light sensing unit 52 is larger than theintensity of the light beam L detected by the light sensing unit 52 whenthe transparent pipe 3 does not transmits the water flow.

The control module 6 receives the first detection signal, and controlsthe heating module 4 whether to continuously produce the thermal energyaccording to the first detection signal. To put it concretely, after thecontrol module 6 receives the first detection signal indicating that thetransparent pipe 3 does not transmit the water flow, the control module6 generates a second control signal according to according to the firstdetection signal, and transmits the second control signal to the heatingmodule 4. Thus, the heating module 4 determines whether to continue toproduce thermal energy or stop producing the thermal energy according tothe second control signal, so as to prevent possible damage and dangercaused by that the heating module 4 continuously heats while no waterflow flows therein. Practically, the control module 6 can be amicrocontroller unit (MCU), a central processor unit (CPU), or at leastone of a software or hardware for storing control commands and forcontrolling each function modules of the present disclosure, and thepresent disclosure is not limited thereto.

The gas/liquid mixing module 7 is used to convert the fluid (comprisingthe hot water flow and water steam) output from the water outputting endof the heating module 4 to the liquid hot water flow, so as to preventfrom the spreading of the water steam, and to increase the thermalenergy conversion efficiency. Practically, the gas/liquid mixing module7 is a thin and long tube, and the present disclosure is not limitedthereto. The outlet 9 is for example a water feeding valve.

In addition, the water feeding device of instantaneous heating type Acan further comprises an input module (not shown in the drawings), andthe input module is electrically connected to the control module 6. Theinput module provides the user to manually set the output amount of thewater flow output by the water feeding device of instantaneous heatingtype A (i.e. the amount of the water flow drawn from the water tank 1 bythe pump 2), and to manually set the temperature of the output waterflow (i.e. the thermal energy produced by the heating module 4).Practically, the input module can be a knob, a push button, a dipswitch, or a touch control display panel, and the present disclosure isnot limited thereto.

[Another One Exemplary Embodiment of Water Feeding Device ofInstantaneous Heating Type]

Referring to FIG. 3, FIG. 3 is a function block diagram of a waterfeeding device of instantaneous heating type according to another oneexemplary embodiment of the present disclosure. As shown in FIG. 3, thewater feeding device of instantaneous heating type A′ comprises a watertank 1, a pump 2, a transparent pipe 3, a heating module 4, acontactless sensing module 5, a control module 6, a gas/liquid mixingmodule 7, an outlet 8, and a water line sensing module 9. Since the mostfunction modules of the water feeding device of instantaneous heatingtype A′ are the same as those of the water feeding device ofinstantaneous heating type A, operations and connections of the samefunction modules are not described again in the exemplary embodiment.

Being different from the water feeding device of instantaneous heatingtype A of the previous exemplary embodiment, the water feeding device ofinstantaneous heating type A′ in the exemplary embodiment furthercomprises the water line sensing module 9. The water line sensing module9 is disposed corresponding to the water tank 1 and electricallyconnected to the control module 6. The water line sensing module 9detects the water line of the water flow stored in the water tank 1, andgenerates a second detection signal accordingly. The control module 6obtains the water storage amount of the water tank 1 according to thesecond detection signal. In practical operation, when the water linesensing module 9 detects the water line of the water tank 1 is less thana predetermined threshold, the control module 6 generates the firstcontrol signal according to the second detection signal to the pump 2,so as to indicate the pump 2 to stop drawing the water flow from thewater tank 1, and to notice the user refills the water-flow to the watertank 1, or to notice the water feeding device of instantaneous heatingtype A′ to automatically refill the water flow of the water tank 1. Inaddition, the predetermined threshold can be preset before themanufacturer provides the water feeding device of instantaneous heatingtype A′, or set by the user requirement, and the present disclosure isnot limited thereto.

Please refer to FIG. 4, the disposed position and the operation of thewater line sensing module 9 are depicted in details, wherein FIG. 4 is alateral view showing a water line sensing module and a water tankaccording to one exemplary embodiment of the present disclosure. Asshown in FIG. 4, the water line sensing module 9 comprises anaccommodation tube 90, a magnetic floating body 92, and a plurality ofHall sensors 94. The bottom side of the accommodation tube 90 isconnected to the water tank 1, such that the water line of theaccommodation tube 90 varies with the water line of the water tank 1;that is, when the water line of the water tank 1 is dropped, the waterline of the accommodation tube 90 is dropped, too. The magnetic floatingbody 92 is disposed in the accommodation tube 90, and the position ofthe magnetic floating body 92 in accommodation tube 90 varies with therising/dropping of the water line of the accommodation tube 90. Thepresent disclosure does not limit the radius of the material of theaccommodation tube 90 and the outline shape of the magnetic floatingbody 92.

The Hall sensors 94 are alternately disposed on an outer wall of theaccommodation tube 90 and electrically connected to the control module6. In practical operation, the Hall sensors 94 generate the secondcontrol signal according to a magnet filed variation due to a differentposition of the magnetic floating body 92 in the accommodation tube.That is, when the water line of the water tank 1 changes, since theposition of the magnetic floating body 92 in the accommodation tube 90changes with the change of the water line of accommodation tube 90, themagnet filed changes. Thus, the Hall sensors 94 can detect the waterline of the water tank 1 according to the magnet filed variation, andtransmit the generated second detection signal to the control module 6,and the control module 6 can determine whether to continuously draw thewater flow from the water tank 1. In addition, the present disclosuredoes not limit the number and spacing distance of the Hall sensors 94.The person with ordinary skill in the art may design a reasonable numberand spacing distance of the Hall sensors 94 according to the practicalusage condition.

[Exemplary Embodiment of Control Method Used in Water Feeding Device ofInstantaneous Heating Type]

Referring to FIG. 3 and FIG. 5, FIG. 5 is a flow chart of a controlmethod used in the water feeding device of instantaneous heating typeaccording to one exemplary embodiment of the present disclosure. Thewater feeding device of instantaneous heating type A′ should beelectrically connected to the external power source (not shown in thedrawings), and has the water tank 1, the transparent pipe 3, and theheating module 4, wherein the transparent pipe 3 is disposed between thewater tank 1 and the heating module 4, and the heating module 4 is usedto convert the electrical energy of the external power source to thethermal energy.

As shown in FIG. 5, at step S50, the water feeding device ofinstantaneous heating type A′ generates a light beam toward thetransparent pipe 3. Next, at step S52, the water feeding device ofinstantaneous heating type A′ detects intensity of the light beampropagating through the transparent pipe 3 to generate a first detectionsignal accordingly, wherein the when the light beam propagates thetransparent pipe 3 and the transparent pipe 3 transmits the water flow,due to the refraction of the light beam, the intensity of the detectedlight beam is larger than the intensity of the detected light beam whenthe transparent pipe 3 does not transmit the water flow. Finally, atstep S54, the water feeding device of instantaneous heating type A′controls the heating module 4 whether to continuously produce thethermal energy according to the first detection signal.

It is preferred that the water feeding device of instantaneous heatingtype A′ further comprises the pump 2, and the pump 2 determines whetherto draw the water flow from the water tank 1 to the heating module 14according to the first control signal.

Then, the water feeding device of instantaneous heating type A′ maydetect the water line of the water flow stored in the water tank 1, andgenerate the second detection signal accordingly. When that the waterline of the water tank 1 is less than a predetermined threshold isdetected, the water feeding device of instantaneous heating type A′further controls the pump 2 to stop drawing the water flow from thewater tank 1 to the heating module 4.

Next, a magnetic floating body and a plurality of Hall sensors are usedto detect the water line of the water tank 1. The magnetic floating bodyhas the different position corresponding to the water line of the waterbank 1, and the Hall sensors are alternately disposed at differentpositions in the water tank 1, such that the second detection signal isgenerated according to the magnet field variation due to a differentposition of the magnetic floating body.

[Possible Result of Exemplary Embodiment]

Accordingly, the exemplary embodiments of the present disclosure providea water feeding device of instantaneous heating type and control methodthereof. Since the refraction indices of the water and air differentfrom each other, the water feeding device of instantaneous heating typeuses a contactless sensing module disposed at an outside of thetransparent pipe connected between the water tank and the heating moduleto detect whether the water flow continuously flows into the heatingmodule. When that the water flow does not flow into the heating moduleis detected, the heating module is turned off and stop generating thethermal energy. In addition, the water feeding device of instantaneousheating type further uses a water line sensing module to detect whetherthe water line of the water tank is sufficient. When that the water lineof the water tank is less than the predetermined threshold is detected,the pump is controlled to stop drawing the water flow from the waterbank. Therefore, the water feeding device of instantaneous heating typeand the control method thereof use the contactless sensing module andthe water line sensing module to control the heating module and the pumpto operate efficiently, so as to prevent the damage of the heatingmodule and the possible danger. That is, the water feeding device ofinstantaneous heating type and the control method has the safety andpracticality.

The above-mentioned descriptions represent merely the exemplaryembodiment of the present disclosure, without any intention to limit thescope of the present disclosure thereto. Various equivalent changes,alternations or modifications based on the claims of present disclosureare all consequently viewed as being embraced by the scope of thepresent disclosure.

What is claimed is:
 1. A water feeding device of instantaneous heating type, electrically connected to an external power source, comprising: a water tank; a transparent pipe, one end thereof is connected to the water tank; a heating module, connected to another one end of the transparent pipe, used to convert electrical energy of the external power source to thermal energy, and heat water flow injected from the water tank accordingly; a contactless sensing module, disposed at an outside of the transparent pipe, comprising: a lighting unit, used to generate a light beam toward the transparent pipe; and a light sensing unit, disposed opposite to the lighting unit, used to detect intensity of the light beam propagating through the transparent pipe to generate a first detection signal accordingly; and a control module, electrically connected to the heating module and the contactless sensing module, used to receive the first detection signal, and control the heating module whether to continuously produce the thermal energy according to the first detection signal.
 2. The water feeding device of instantaneous heating type according to claim 1, wherein when the light beam propagate through the transparent pipe and the transparent pipe transmits the water flow, due to refraction of the light beam, the intensity of the light beam detected by the light sensing unit is larger than that while the transparent pipe does not transmit the water flow.
 3. The water feeding device of instantaneous heating type according to claim 1, wherein the water feeding device of instantaneous heating type further comprises a pump, the pump is connected to the other one end of the transparent pipe, the heating module, and the control module, the pump is controlled by the control module, and determines whether to continuously draw the water flow from the water tank to the heating module according a control signal generated by the control module.
 4. The water feeding device of instantaneous heating type according to claim 3, wherein the water feeding device of instantaneous heating type further comprises a water line sensing module, the water line sensing module is disposed in the water tank, electrically connected to the control module, and used to detect a water line of the water flow stored in the water tank to generate a second detection signal accordingly, such that the control module obtains water storage amount of the water tank through the second detection signal; when the water line sensing module detects the water line of the water tank is less than a predetermined threshold, the control module generates the control signal according to the second detection signal, and the control signal is used to indicate the pump to stop drawing the water flow from the water tank.
 5. The water feeding device of instantaneous heating type according to claim 4, wherein the water line sensing module comprises: an accommodation tube, a bottom side thereof is connected to the water tank, such that a water line of the accommodation tube varies with the water line of the water tank; a magnetic floating body, disposed in the accommodation tube; and a plurality of Hall sensors, alternately disposed on an outer wall of the accommodation tube, and electrically connected to the control module, wherein the Hall sensors generates the second signal according to a magnet filed variation due to a different position of the magnetic floating body in the accommodation tube.
 6. A control method used in a water feeding device of instantaneous heating type, the water feeding device of instantaneous heating type is electrically connected to an external power source, and has a water tank, a transparent pipe, and a heating module, wherein the transparent pipe is disposed between the water tank and the heating module, the heating module is used to converts electrical energy of the external power source to a thermal energy, and the control method comprises: generating a light beam toward the transparent pipe; detecting intensity of the light beam propagating through the transparent pipe, and generating a first detection signal accordingly; and controlling the heating module whether to continuously produce the thermal energy according to the first detection signal.
 7. The control method used in the water feeding device of instantaneous heating type according to claim 6, wherein when the light beam propagate through the transparent pipe and the transparent pipe transmits the water flow, due to refraction of the light beam, the intensity of the light beam detected by the light sensing unit is larger than that while the transparent pipe does not transmit the water flow.
 8. The control method used in the water feeding device of instantaneous heating type according to claim 6, wherein the water feeding device of instantaneous heating type further comprises a pump, the pump determines whether to continuously draw the water flow from the water tank to the heating module according to a control signal.
 9. The control method used in the water feeding device of instantaneous heating type according to claim 8, further comprising: detecting a water line of the water tank to generate a second detection signal accordingly, and when the water line sensing module detects the water line of the water tank is less than a predetermined threshold, controlling the pump to stop drawing the water flow from the water tank to the heating module.
 10. The control method used in the water feeding device of instantaneous heating type according to claim 9, wherein to detect the water line of the water tank, a magnetic floating body and a plurality of Hall sensors are used, the magnetic floating body has a different position corresponding to the water line of the water bank, and the Hall sensors are alternately disposed at different positions in the water tank, such that the second detection signal is generated according to the magnet field variation due to a different position of the magnetic floating body. 